safe_mode for ISPs

Keywords: safe_mode security ISP restricting access Safe mode is not safe enough for ISP's with malicious users. This is the reason why many ISP dare not run PHP on their web-hosts. For ISP's to run PHP it must fulfill to the following requirements: #1. Protect users against each others - spying in other users' files #2. Protect against abuse of the ISP's resources - memory - CPU - bandwidth #3. Protect against cracking/port-scanning other sites In a quick review of the functions in PHP3 we have found the following problems. The problems existed even with safe mode on. a. symlink() In safe mode you can symlink("/etc/passwd","passwd") and then read the password file and the same goes for the other users' files. This does not fulfill requirement #1. b. set_time_limit() By expanding the max_execution_time you can abuse CPU time. This does not fulfill requirement #2. c. fsockopen() With fsockopen you can make a port scanning of a remote network. This does not fulfill requirement #3. We are confident that there are a lot more functions that can be abused by a malicious user. We therefore suggest creating a working group that will make a safe_mode that is safe enough for ISPs to use. best regards Hans Schou and Ole Tange